Additives for hydrogenated resins

ABSTRACT

Additives for hydrogenated resins obtainable by using the following components: 
     a) bifunctional perfluoropolyethers having a —COOR end group, optionally in admixture with monofunctional perfluoropolyethers having a —COOR end group, 
     b) mono, bi or polyfunctional hydrogenated monomers having functional groups able to react with the —COOR end groups of compound a); 
     c) polyolefins having functional groups able to react with the block oligomer/polymer obtained by reaction of a) with b), preferably said functional groups being obtained by grafting with maleic anhydride; 
     reacting in a first step a) with b), until disappearance of the —COOR group of component a), and in a second step the product obtained from the reaction of a) with b) with the functionalized polyolefins c).

The present invention relates to fluorinated compounds usable asadditives for hydrogenated resins, for example polyolefins, elastomersand polymers from, polycondensation. The additives of the invention donot negatively affect the processability during the extrusion ofhydrogenated resins, on the contrary they improve it and the finishedmanifactured article shows an improved mould release. Besides, thefinished manufactured article (hydrogenated resin added with theinvention additives) shows lasting improved surface properties.

More particularly the present invention relates to additives formed byperfluoropolyether chains and functionalized polyolefins. Said additivescan be obtained in solid form (granules, powder or pellets) and arecompatible with hydrogenated polymers with which they form homogeneousmixtures. Therefore masterbatches at various additive concentrations,even very high, can be prepared, with hydrogenated resins, even of theorder of 50% by weight of additive.

In the prior art the use of fluorinated additives to improve the polymerproperties is known. U.S. Pat. No. 4,278,776 describes the use ofpolyamides obtained from perfluoropolyethers as process additives forblends of curable fluorinated rubbers. Tests carried out by theApplicant showed that polyamides obtained from perfluoropolyethers donot allow to prepare masterbatches with hydrogenated resins at highconcentration of this additive. Besides even at low concentrations ofthis additive a homogeneous masterbatch is not obtained. Therefore thesemasterbatches are not in practice usable in extrusion since finishedmanufactured articles are obtained having non uniform properties. (Seethe comparative Examples). U.S. Pat. No. 5,061,759 describesperfluorinated perfluoropolyether additives or having bromine end groupsfor fluorinated rubbers curable by peroxidic way, the additive amountbeing in the range 0.5-1% by weight. These additives improve theprocessability of the fluorinated rubbers and the mould release. Alsothese additives when used for hydrogenated resins to obtainmasterbatches to be used for preparing manufactured articles give thesame drawbacks of the polyamides obtained from perfluoropolyethers.

U.S. Pat. No. 3,899,563 describes. monofunctionalized fluoro alkyladditives, such as amides, diamides, triazines, substituted ureas, forthermoplastic resins. In said patent no mention is made to thepossibility to prepare masterbatches of above additives withhydrogenated resins, in particular no mention is made to polyolefins.

U.S. Pat. Nos. 5,143,963 and 5,286,773 describe fluorinated additivesfor hydrogenated thermoplastic polymers. Among the various additives,perfluoropolyether additives are mentioned and only perfluoropolyethershaving perfluorinated end groups are exemplified. The additive amount isin the range 0.01%-<1% by weight. The finished manufactured articleshave a surface tension lower than that of the thermoplastic polymer andshow a higher fluorine content on the surface than inside the compound.The manufactured article is characterized by a higher hydrophobicity andantiadherence, a lower friction and a smoother surface. The fluorinatedcompounds used as additives can be under the form of oil, grease, orrubber. With these additives it is not possible to prepare masterbatcheshaving a high content of additives, for example of 20% (see thecomparative Examples). Besides, to additivate the liquid fluorinatedcompounds, particular equipments must be used so as to have a highmixing efficiency and therefore twin-screw extruders are used. Testscarried out by the Applicant have shown that by using the standardsingle screw extruders, widely used industrially, it is not possible toprepare masterbatches even at concentrations lower than 1% by weight.

U.S. Pat. No. 5,025,052 describes fluorinated dioxazolidinones asadditives for thermoplastic resins. Also in this case no mention is madeto the preparation of masterbatches with high additive concentrations.

U.S. Pat. Nos. 5,681,963 and 5,789,491 describe the use of imides basedon monofunctional perfluoroalkyl compounds as additives in theproduction of fibers (polyolefins, polyesters, polyamides)water-repellent, alcohols and fluids having a low surface tension. Insaid patents it is stated that fluorinated polymer derivatives are notsuitable for this kind of use due to their insufficient capability tomigrate on the surface. Patent applications WO 97/22,576 and WO97/22,659 describe the use of mono- and diesters of fat acids, excludingthe stearic acid, with monofunctional fluoroalkyl alcohols to giveidro/oilrepellent properties to polymer fibres, in particularpolypropylene fibres. Also in this case the polymer additives areconsidered unsuitable as above mentioned.

Patent application WO 99/23,149 describes the preparation ofmanufactured articles resistant to creaking by addition of a genericfluorinated additive under the form of oil, wax or rubber, in amounts inthe range 0.01%-5% by weight, to a hydrogenated polymer such aspolyurethane or both thermoplastic and thermosetting resins. Alsoperfluoropolyethers even having functional end groups, and theirhomologues having a higher molecular weight, with a fluorine contenthigher than 50% belong to the class of fluorinated additives. In saidpatent application it is indicated that when the polymer isthermoplastic, to prepare these compositions the polymer is melted andmixed in the liquid state with the fluorocarbon additive, and theadditive feeding into the mixing equipment takes place by additiondevices for liquids. Therefore this mixing process shows the drawback torequire a particular equipment since the components, as said, must beadded at the liquid state. Also perfluoropolyethers havingperfluoroalkyl end groups are indicated as usable. Also for said patentapplication the above same considerations are valid.

Patent application WO 99/23.148 describes manufactured articlesresistant to abrasion obtained by addition of 0.01% up to 1% of one ofthe fluorinated additives described in the previous patent applicationfor thermosetting resins. No reference is made to masterbatches.

Patent application WO 99/23,147 describes linear or crosslinked polymershaving a Shore A hardness from 10 to 90, modified by addition offluorinated additives in amounts between 1 and 10%, to obtain animproved abrasion resistance. In above patent application fluorinatedadditives oils, rubbers or greases formed by fluorocarbons which cancontain functional groups are indicated as suitable. The mixingequipment is the one used to mix liquid compounds described in patentapplication WO 99/23,149 and therefore also this mixing process showsthe same above mentioned drawback.

U.S. Pat. No. 5,451,622 describes the use of partially fluorinatedpiperazines with monofunctional fluoroalkyl segments, containing afluorine amount between 20 and 70% by weight as hydro/oilrepellentadditives for hydrogenated resins, such as for example polypropylene.Also in said patent no mention is made to masterbatches having a highconcentration of additive.

Generally according to the above prior art the fluorinated additives canbe used as process additives, or as additives to give improved surfaceproperties to the finished manufactured article. The addition procedureof the fluorinated additive into the hydrogenated resin is generally acomplicated step and requires, as seen, particular equipments for thedosage of the fluorinated additive in extrusion. The additive indeed isoften under the liquid form and high efficiency equipments as twin-screwextruders for the homogeneization with the resin are required. With theliquid fluorinated additives of the prior art it is difficult to preparemasterbatches having a high additive concentration in the hydrogenatedresin, in particular at concentrations higher than 10% by weight ofadditive. When perfluoropolyethers are used as additives, masterbatcheshaving a maximum concentration of additive of 1-2% by weight can beprepared. (See comparative Examples). This is due to the substantialimmisciability of the fluorinated additive with the hydrogenated resinwhich requires the use, as seen, of particular equipments. The lack ofhomogeneity in the masterbatch implies a difficult dosage of theadditive in the final manufactured article, with the obtainment ofmanufactured articles which have no reproducible properties. This is adrawback from the industrial point of view. A further drawback isrepresented by the limited permanence in the time of the fluorinatedadditive in the manufactured article. In fact the additive can beremoved by thermal effect during the working steps, or by—washing away,or by mechanical action, for example abrasion, with loss of the surfaceproperties of the manufactured article and possible environmentalpollution. At any rate no mention is made to masterbatch of additive inhydrogenated resin with high additive content, of the order of 50%. Thepossibility to have available masterbatches with a high content ofadditive allows to have masterbatches with a more uniform concentrationof additive. Furthermore said masterbatches can be used withhydrogenated resins even different from those used to preparemasterbatches. This allows to obtain final resins having a more uniformdistribution of the additive and therefore with substantiallyhomogeneous properties and thus lower wastes during the production ofmanufactured articles.

The need was felt to have available fluorinated additives having thefollowing properties:

were available in solid form (granules or pellets), and thereforemeasurable with normal loading hoppers, without necessarily requiringthe use of particular batcher,

were easily compatible with the hydrogenated resins, both thermoplasticand thermosetting, for example polyolefins, polyolefin rubbers,polyesters, polyamides, polyurethanes, also using single screwextruders,

confer to the finished compound lasting surface hydro- and oilrepellenceproperties, abrasion resistance, low friction coefficient, improvedmould release,

possibility to prepare masterbatches at various, even very high,additive concentrations, with hydrogenated resins, even of the order of50% by weight of additive.

The Applicant has surprisingly and unexpectedly found additivescontaining perfluoropolyether oligomers or polymers and functionalizedpolyolefins, having the combination of the above properties.

An object of the present invention are additives for hydrogenatedresins, formed by functionalized perfluoropolyethers and functionalizedpolyolefins, said additives obtainable by using the followingcomponents:

a) bifunctional perfluoropolyethers having a —COOR end group, optionallyin admixture with monofunctional perfluoropolyethers having —COOR endgroup, wherein R═H, C₁-C₁₀ alkyl, the number average molecular weight ofbifunctional and monofunctional perfluoropolyethers being in the range500-5,000, preferably 900-3,000;

b) mono, bi or polyfunctional hydrogenated monomers having functionalgroups capable to react with the —COOR end groups of compound a);preferably said functional groups of the hydrogenated monomers areaminic groups,

c) polyolefins having functional groups, preferably formed by C₂-C₄monomers, wherein said functional groups are capable to react with theblock oligomer/polymer obtained by reaction of a) with b), preferablysaid functional groups being obtained by grafting with maleic anhydride;

reacting in a first step a) with b), or a) with mixtures of monomers b)having a different functionality, until disappearance of the —COOR groupof component a), and in a second step the product obtained from thereaction of a) with b) with the functionalized polyolefins c).

The additive of the invention can optionally comprise neutralperfluoropolyether oils having a molecular weight in the range2,000-10,000 (compound d)).

The amounts of each of the components a) -d), expressed as percentagesby weight, are the following:

component a) 30-70% by weight;

component b) 1-30% by weight;

component c) 10-70% by weight;

component d) 0-20% by weight;

the sum of a)+b)+c)+d) being equal to 100% by weight.

The bifunctional (per)fluoropolyethers and the monofunctionalperfluoropolyethers (component a)) have one or more of the followingunits statistically distributed along the chain: (C₃F₆O); (CFYO) whereinY is F or CF₃; (C₂F₄O); (CF₂(CF₂)_(x′)CF₂O) wherein x′ is an integerequal to 1 or 2; (CR₄R₅CF₂CF₂O) wherein R₄ and R₅ are equal or differentfrom each other and selected from H, Cl, and wherein one fluorine atomof the perfluoromethylene unit can optionally be substituted with H, Clor (per)fluoroalkyl, having for example from 1 to 4 carbon atoms.

The preferred bifunctional compounds of a) are the following with theperfluorooxyalkylene units statistically distributed along the chain:

(a′)—CF₂—O—(CF₂CF₂O)_(p′)(CF₂O)_(q′)—CF₂—  (VIII)

wherein:

p′ and q′ are numbers such that the q′/p′ ratio is comprised between 0.2and 2 and the number average molecular weight is in the above range;

 (b′)—CFX′^(I)—O—(CF₂CF(CF₃)O)_(r′)—(CF₂CF₂O)_(s′)—(CFX′^(I)O)_(t′)—CFX′^(I)—  (IX)

wherein:

X′^(I) is —F or —CF₃; r′, s′ and t′ are numbers such that r′+s′ is inthe range 1-50, the t′/(r′+s′) ratio is in the range 0.01-0.05, r′+s′being different from zero, and the molecular weight is in the aboverange;

(c′)—CF(CF₃)(CFX′^(I)O)_(t′)(OC₃F₆)_(u′)—OR′_(f)O—(C₃F₆O)_(u′)(CFX′^(I)O)_(t′)CF(CF₃)—  formula(X)

wherein:

R′_(f) is a C₁-C₈ perfluoroalkylene; u′+t′ is a number such that thenumber average molecular weight is in the above range; t′ can also beequal to zero; X′^(I) is as above indicated;

(d′)—CF₂CF₂O—(CF₂(CF₂)_(x′)CF₂O)_(v′)—CF₂CF₂—  (XI)

wherein:

v′ is a number such that the molecular weight is in the above range, x′is an integer equal to 1 or 2;

(e′)—CF₂CH₂—(OCF₂CF₂CH₂O)_(w′)—OR′_(f)O—(CH₂CF₂CF₂O)_(w′)—CH₂CF₂—  (XII)

wherein:

R′_(f) is a C₁-C₈ perfluoroalkylene; w′ is a number such that the numberaaverage molecular weight is in the above range; the end groups of thebifunctional perfluoropolyethers component a) being of the —COOR typewherein R═H or C₁-C₁₀ alkyl.

The bifunctional (per)fluoropolyoxyalkylenes are known products and canbe prepared starting from the corresponding (per)fluoropolyoxyalkyleneshaving —COF end groups (see for example patents GB 1,104,482, U.S. Pat.Nos. 3,715,378, 3,242,218, 4,647,413, EP 148,482, U.S. Pat. No.4,523,039, EP 340,740, patent application WO 90/03357, U.S. Pat. No.3,810,874, EP 239,123, U.S. Pat. Nos. 5,149,842, 5,258,110).

The preferred monofunctional perfluoropolyethers which are used in a) inadmixture with bifunctional perfluoropolyethers have the followingstructures:

A—O(C₃F₆O)_(m)(CFYO)_(n)—  IB)

wherein

Y is —F, —CF₃; A′=—CF₃, —C₂F₅, —C₃F₇, —CF₂Cl, C₂F₄Cl;

the C₃F₆O and CFYO units are randomly distributed along the(per)fluoropolyether chain, m and n are integers, the m/n ratio is ≧2, mand n have values such that the molecular weight is within the limitsindicated for component a);

C₃F₇O(C₃F₆O)_(m)—  IIB)

wherein m is a positive integer and is such that the average molecularweight is in the limits indicated for component a);

(C₃F₆O)_(m)(C₂F₄O)_(n)(CFYO)_(q)   IIIB)

wherein:

Y is equal to —F, —CF₃; m, n and q, different from zero, are integerssuch that the number average molecular weight is in the limits indicatedfor component a);

being the end group of the monofunctional perfluoropolyethers —CF₂—COOR,R being as above.

The compounds IB) are for example obtainable by photooxidation ofhexafluoropropene according to the process described in patent GB1,104,482; the compounds IIB) are for example obtainable by ionictelomerization of hexafluoropropene epoxide: see for example U.S. Pat.No. 3,242,218; the compounds IIIB) are for example obtainable byphotooxidation of C₃F₆ and C₂F₄ mixtures by the processes described inU.S. Pat. No. 3,665,041.

The amount of monofunctional perfluoropolyethers in admixture with thebifunctional perfluoropolyethers is in the range 0-90% by weight of themixture a), preferably 5-40%.

Examples of component b), when the functionality is aminic, are thefollowing:

(b1) monoamines of formula R₁-NH₂ wherein R₁ is a linear aliphatic orcycloaliphatic C₁-C₂₀ alkyl with a number of carbon atoms of the ringfrom 4 to 6, optionally substituted with C₁-C₄ alkyl groups; or R₁ is anaryl group optionally substituted with linear or branched C₁-C₄ alkylgroups, the total number of the carbon atoms being in the range 6-20; anexample of the amines of formula R₁—NH₂ is stearylamine;

(b2) diamines of formula NR_(2A)R_(3A)—R_(1A)—NH₂, wherein R_(1A)=linearor cycloaliphatic C₂-C₁₂ alkyl radical with a number of carbon atoms ofthe ring from 4 to 6, optionally substituted with C₁-C₄ alkyl groups, orC₆-C₁₂ aryl group; R_(2A) and R_(3A), equal to or different from eachother, are hydrogen or linear or branched C₁-C₅ alkyl group; examples ofdiamines with R_(1A)=alkyl and R_(2A)=R_(3A)=H, are ethylendiamine andhexamethylendiamine; an example of diamine with R_(1A)=aryl isnaphthalendiamine; an example of diamine with R_(1A)=alkyl andR_(2A)=R_(3A)=CH₃ is N,N-dimethylamino-ethylendiamine;

(b3) aromatic tetramines of formula (NH₂)₂—Ar1-Ar1-(NH₂)₂ withAr1=phenyl, optionally substituted with C₁-C₄ alkyl groups; an exampleof aromatic tetramine is the tetramino biphenyl compound.

The preferred monomers b) are stearylamine (b1), still more preferably acompound of the classes (b2) and (b3).

In the component c) the functionalized polyolefins are for example thefollowing polymers: polypropylene homopolymer, copolymers ofpolypropylene, high density polyethylene (HDPE), linear low densitypolyethylene (LLDPE) grafted with functionalized monomers capable toreact with the aminic groups of the reaction product of a)+by. As anexample of grafting monomer the maleic anhydride can be mentioned. Othercomponents c) are copolymers or terpolymers of ethylene containing anethylenic monomer having a second functional group, for example withvinyl acetate, and optionally in the presence of carbon oxide CO, forexample EVA, E/nBa (n-buty-lacrylate) and E/nBA/CO.

The functionalized polyolefins component c) are commercially known andavailable products. For example the resins Fusabond® and Bynel®(DuPont), and the resins Questron® (Montell) can be mentioned.

The perfluoropolyether oils component d) have the same composition ofunits in the chain as described for component a), but they haveperhalogenated end groups of the —CF₂X type, with X=F, Cl, preferablyX=F. Said perfluoropolyethers are obtainable by known processes. See forexample U.S. Pat. Nos. 3,665,041, 2,242,218, 3,715,378 and EP 239,123.

Admixtures of monomers b) having the same chemical function, for examplestearylamine with hexamethylendiamine, can be used in the inventioncomposition.

The additives according to the present invention are obtainable by aprocess comprising the following steps:

1) synthesis of the compound a)+b) by reaction of the functionalizedperfluoropolyether component a), optionally formed by a mixture of abifunctional and monofunctional perfluoropolyether, with thehydrogenated monomer component b), by heating under stirring at atemperature in the range 90°-100° C., and subsequently at 100°-130° C.under vacuum (1 mmHg) to complete the reaction, i.e. until in the IRspectrum the band at 1800 cm⁻¹ of the COOR group linked to —CF₂—disappears;

2) addition, under stirring, in the same reactor, of the functionalizedpolyolefin component c), preferably functionalized with maleicanhydride, and reaction of the mixture by heating at atmosphericpressure for 30-60 minutes at a temperature in the range 180° C.-190°C.; at the end hot discharge of the obtained product.

Step 1 is carried out by introducing in a polycondensation reactor, orin suitable mixing cell, equipped with stirrer, a mixture formed by thefollowing components:

compound a), for example an ethyl or methyl diester of aperfluoropolyether, optionally in admixture with a perfluoropolyethermonoester,

monomer b), optionally in admixture with other monomers b) having adifferent functionality; for example as component b) an aliphatic oraromatic diamine, optionally in admixture with monofunctional and/orpolyfunctional amines having functionality higher than two, can be used;

the molar ratio between the functional groups of b) and a) is in therange 1-1.5, and anyway the amount of b) must be such to cause in thereaction the disappearance of the —COOR groups of a). The temperature ofthe reactor is then brought to a value in the range 90°-100° C., understirring, collecting by distillation the released alcohol. When thedistillation phase at atmospheric pressure is over, the polymer isheated to 100°-130° C. under vacuum (1 mmHg) to complete the reaction.The reaction ends when in the IR spectrum the band at 1800 cm⁻¹ of theCOOR group linked to —CF₂— disappears.

The ratio between the monofunctional monomers and polyfunctionalmonomers of b) can be optimized in function of the molecular weight ofa)+b) one wants to obtain.

The monomers b) react with the bifunctional perfluoropolyethers a),optionally in admixture with monofunctional perfluoropolyethers, givingfor example polyamides and polybenzoimidazoles, the latter obtainablefrom the above mentioned aromatic tetramines (b3).

Optionally, to the compound obtained in the first step, fluorinatedadditives, such as for example the perfluoropolyether oil compound d)can be hot added, under stirring, in the amounts by weight within theabove range.

In step 2) component c), the functionalized polyolefin, preferably withmaleic anhydride, and the reaction product of a) with b) are introducedin the same reactor under stirring. It is heated at atmospheric pressureunder stirring for 30-60 minutes at a temperature of 180°C.-190° C.; thedischarged finished reaction product is a mass of homogeneous plasticmaterial. In the second step the ratio between the functional groups ofthe compound obtained by reaction of a) with b) and the functionalgroups of the functionalized polyolefin ranges from 10 to 0.1 by moles,preferably it is about 1.

The additive obtained at the end is under solid form at room temperatureand higher, generally up to 80° C., being characterized by a meltingpoint generally higher than 80° C., and by a perfluoropolyether contentin the chain higher than 50% by weight.

The so obtained invention additive, preferably after extrusion andpelletization, is used as additive to obtain homogeneous masterbatcheswith hydrogenated resins. The additive concentrations in the masterbatchare in the range 1-50% by weight.

Examples of hydrogenated resins are polyolefins such as HDPE, LLDPE, PPand respective copolymers, polyesters such as PET, polyamides as nylon,rubbers such as EPDM, etc.

The masterbatches are prepared for example by mixing the additive withhydrogenated resins, for example in a mixing cell, at temperatures inthe range 170° C.-190° C. for 15-30 min, or by extrusion, under theoperating conditions used for the hydrogenated resins.

Optionally, the product obtained from the reaction of component a) withcomponent b) of the additive and then reacted with the component c) canbe added to the hydrogenated resin.

For example, the reaction product of a)+b) can be added in a mixing cellor extruder to the hydrogenated resin and then the two phasescompatibilized during the extrusion by adding granules of component c).The masterbatches are macroscopically homogeneous and defects free. Itis industrially advantageous to have available masterbatches having ahigh additive concentration. In this case the masterbatch is used byadding the hydrogenated resin, in subsequent dilutions, until obtainingthe desired fluorine content. During this processing, losses of additiveor its components have not been noticed.n

According to a non binding theory, it is considered that the fluorinatedpart, the perfluoropolyether compound a) chemically linked to thepolyolefin c) cannot be extracted during the steps of the obtainment ofthe masterbatch. Besides, it has been found that the additive is notvolatilized with the mentioned thermal treatments.

The finished manufactured article obtainable by mixing the masterbatcheswith hydrogenated resins is characterized by the combination of theabove properties: hydrophobicity, resistance to low surface tensionliquids, resistance to abrasion, and low friction coefficient, andmaintenance of these properties in the time.

A further advantage of the invention additive unexpectedly found by theApplicant is that it can be used also to carry in the hydrogenated resinother fluorinated additives, such as non functionalizedperfluoropolyether oils (component d)), without requiring the use inextrusion of liquid batchers, obtaining an improved final homogeneityand persistence of the perfluoropolyether oil, in the manufacturedarticle in use. Indeed, as said, a drawback of the use of non reactiveperfluoropolyether oils as additives for hydrogenated resins is thattheir effect on the hydrogenated resins is very limited in the time.

The additive of the present invention is characterized by itsrheological properties, thermal analysis (differential calorimetry andthermogravimetry) and IR spectroscopy.

As already said, the additive of the invention improves the processingproperties and confers also properties of improved mould release fromthe of the finished manufactured article.

The manufactured article can be subjected to a second thermal treatmentby heating at a temperature in the range 100°-140° C. to further improvethe above mentioned surface properties.

The following Examples illustrate the invention without limiting thescope thereof.

EXAMPLES

Analytical Methods

The dynamic viscosity was determined at 30° C., Ares rheometer havingparallel plates, frequency 0.83 rad/s.

The aminic equivalent weight NH₂ was determined by potentiometertitration, dissolving about 5 g of polymer in 50 ml of a 9:1 solution(v/v) of trichlorotrifluoroethane:methanol, and titrating by apotentiograph with an alcoholic solution of HCl 0.1 N.

The thermal transitions (Tg and Tm) were determined by a Perkin Elmer®DSC 2 instrument by using the following thermal procedure: heating from50° to 180° C. at 10° C./min, isotherm at 180° C. for 5 min, coolingfrom 180° C. to 50° C. at 100C./min, isotherm at 50° C. for 2 min,heating from 50° C. to 180° C. at 10° C./min.

The tensile properties were determined at 23° C. according to ASTM D1708(5 mm/min rate) with an Instrom® mod. 1185 dyna-mometer.

The static contact angle with n-hexadecane was determined by the methodof the sessile drop with a Kruss® G23 instrument at room temperature.The angle measure was taken by photograph after 30 seconds of contact ofthe drop with the surface.

Example 1

Synthesis of the Polyamide Obtained by Reaction of Ethylendiamine with aPerfluoropolyether Bifunctional Ester

30 g of ethylendiamine and 1 Kg of an oil formed by theperfluoropolyether methyl diester having molecular weight 2,000 and thefollowing structure:

CH₃OCOCF₂O(CF₂CF₂O)_(p)(CF₂O)_(q)CF₂COOCH₃ with p/q=2  (1-A)

are fed into a 2 liters polycondensation reactor equipped with stirrer.

The reaction mixture is heated under nitrogen atmosphere for 4 hours,distilling the methanol released during the polycondensation. At the endthe inside of the reactor is connected with the vacuum source (1 mmHg)heating at 100° C. for further 4 hours. At the end the initial pressureis restored in the reactor and the perfluoropolyether polyamidicderivative is hot discharged from the reactor bottom under the form of aviscous oil.

In the IR spectrum of the polyamidic derivative the absorption band at1800 cm⁻¹ of the —CF₂COOCH₃ groups is absent, therefore all the estergroups of the starting perfluoropolyether were converted to amidicgroups (1690 cm⁻¹). The polyamide shows the following physicalcharacteristics:

Viscosity: 32.000 Poise (3.2×10³ Pa).

Thermal transitions (DSC, 20° C./min): −104° C.; −20° C.

Aminic equivalent weight NH₂: 23,000 g/eq.

Example 2

Synthesis and Characterization of the Polyamide Obtained by Reaction ofHexamethylendiamine with a Perfluoropolyether Bifunctional Ester

60 g of hexamethylendiamine and 1 Kg of perfluoropolyether methyldiester oil having molecular weight 2,000 and the following structure:

CH₃OCOCF₂O(CF₂CF₂)_(p)(CF₂O)_(q)CF₂COOCH₃ with p/q=2

are fed in a 2 liters polycondensation reactor equipped with tapestirrer.

The reaction mixture is heated under nitrogen atmosphere for 4 hours,distilling the methanol polycondensation by-product. Then the vacuumsource (1 mmHg) is connected, heating at 120° C. for further 4 hours.The perfluoropolyether polyamide is hot discharged from the reactorbottom under the form of a viscous oil.

In the IR spectrum of the polyamide the absorption band at 1800 cm⁻¹ isabsent, characteristic of the —CF₂COOCH₃ groups. Therefore all the estergroups are converted to amidic groups (band at 1690 cm⁻¹). The polyamideis characterized in terms of thermal transitions (by DSC) and viscosity(flow curve at 30°):

Viscosity: 70,000 Poise (7.10³ pa).

Thermal transitions (DSC, 20° C./min): −107° C.; −40° C.

Example 3

Synthesis and Characterization of the Polyamide Obtained by Reaction ofBis-stearylamide with a Perfluoropolyether Bifunctional Ester

In a 2 liters 3-necked glass flask equipped with mechanical stirring,nitrogen atmosphere and distillation retort, 500 g of theperfluoropolyether diester of formula (1-A) but having molecular weight1,500, and 180 g of stearylamine are introduced. The reation mixture isheated under stirring to 70°-80° C. distilling the released methylalcohol. After a reaction time of 4 hours the vacuum source (1 mmHg) isconnected, which is maintained for 2 hours. It is cooled and a solidhaving a waxy consistency is discharged from the reactor. The IRanalysis shows the absence of the band at 1800 cm⁻¹ (ester group linkedto a CF₂ group).

Thermal transitions (DSC, 20° C./min): −80° C. (Tg); +40° C. (Tm).

Example 4

Preparation of the Additive by Reaction of a PolyamidicPerfluoropolyether Derivative with Functionalized Polyethylene

500 g of the fluorinated polyamide obtained in Example 2 and 500 g ofgranules of polyethylene functionalized with maleic anhydride, havingthe following characteristics: Melt Flow Index MFI (190° C., 2.16 Kg,ASTM D1238) 4.2 g/10 min; content in maleic anhydride 0.4% by weight; Tm80° C., are introduced in a 2 liters polycondensation reactor.

The mass is heated under stirring to 190° C. for one hour. At the endabout 900 grams of a white solid, having a consistency like plastic,having the following properties, are discharged:

Thermal transitions (DSC, 20° C./min): −100° C. (Tg); +93° C. (Tm)

Thermal stability (TGA, dynamic at 10° C./min from 20° C. to 700° C.):T^(1%) (temperature at which a weight loss of 1% of the tested sampleoccurs): 362° C.

Example 4b

Characterization of the Mechanical Properties of the Additive of Example4

The additive of Example 4 is moulded in press (200° C., 5 min) obtainingspecimens which are subjected to tensile mechanical anddynamic-mechanical characterization by an Instrom® mod. 1185 dynamometeraccording to ASTM D1708 and by an Ares®3-A25 spectrometer havingparallel plates according to ASTM D4065 with a heating gradient of 2°C./min and 6.28 rad/s frequency.

The moulded additive is a solid. Indeed the specimens maintain thedimensional stability even after heating at 50° C. for 72 hours. Thedeformation imposed with the ASTM test (500%) is not recovered afterspecimen cooling to room temperature. It is noticed that the deformationrecover is lower than 1% after conditioning of the specimens for 24 h atroom temperature. The dynamic-mechanical additive spectrum shows, atroom temperature, a modulus G′ value (elastic component) of about 1-2MPa and a G″ value (viscous component) of about 0.01 MPa.

Over the melting point (110°-120° C.) G″>G′.

The additives of the invention therefore are not waxy or rubberysubstances, but they are more properly classifiable as plasticmaterials.

Example 5

Preparation of the Additive by Reaction of a PolyamidicPerfluoropolyether Derivative with Functionalized Polypropylene

500 g of the fluorinated polyamide obtained in Example 1 and 500 g ofgranules of polypropylene functionalized with maleic anhydride, havingthe following characteristics: Melt Flow Index (determined as in Example4) 28 g/10 min; content in maleic anhydride 0.6% by weight; Tm 152° C.,are introduced in a 2 liters polycondensation reactor

The mass is heated under stirring to 190° C. and kept at thistemperature for one hour. At the end about 900 grams of a white solid,having a consistency like plastic, with the following properties, aredischarged:

MFI (190° C., 2.16 kg, ASTM D 1238) 210 g/10 min.

Thermal transitions (DSC, 20° C./min): −100° C. (Tg); +150° C. (Tm).

Thermal stability (TGA, dynamic at 10°C./min from 20° C. to 700° C):T^(1%) (temperature at which a weight loss of 1% of the tested sampleoccurs): 350° C.

Example 6

Preparation of an Additive of the Invention in Admixture with a NonReactive Perfluoropolyether Oil (Fomblin® YR) and Preparation ofMasterbatches with Polyolefins

A mixture formed by the following components is prepared: 450 g of thepolyamide obtained in Example 1, 50 g of perfluoropolyether having nonreactive (perfluorinated) end groups Fomblin® YR 1800 and 500 g offunctionalized polypropylene having the proprties indicated in theprevious Example 5 (MFI 115, anhydride 0.6% by weight).

The process mentioned in example 4 is followed.

After 2 hours of mixing, a white plastic, macroscopically homogeneous,solid is discharged, without emerging signs of oily residues on thesolid surface or on those of the reactor.

The product is added to polyolefins such as polypropylene andpolyethylene to give homogeneous masterbatches having additiveconcentrations in the range 5-20%, without noticing the typical problemscaused by the use of non reactive PFPE oils.

Example 7

Use of the Additive of Example 4 as Additive for HDPE (Processing Aid)

A masterbatch formed by 20 parts by weight of additive of Example 4 with80 parts by weight of HDPE was prepared. The used polyolefin ischaracterized by MFI of 1 g/10 min (190° C./2.16 Kg). The masterbatchwas prepared by charging the components in a Brabender mixing cell at180° C. for 30 min (30 rpm rate). The masterbatch cold discharged fromthe cell appears as a macroscopically homogeneous white plastic solid.The masterbatch was further diluted with HDPE to an additive content of4% and 1% respectively, by adding further HDPE in Brabender cell at 170°C. for 30 min (30 rpm rate).

The 20% and 4% masterbatches were then moulded in a plate press (230° C.for 5 min) and characterized in terms of mechanical (tensile),dynamic-mechanical and thermal (DSC calorimetry) properties to evaluatethe homogeneity degree of the additive distribution and its effect onthe most important physical properties of the polyolefin. The tensileproperties were determined at 23° C. by an Instrom® mod. 1185dynamometer according to ASTM D1708 (5 mm/min rate), while the thermaltransitions (meltings) were determined by using the following thermalprocedure: heating from 50° to 180° C. at 10° C./min, isotherm at 180°C. for 5 min, cooling from 180° C. to 50° C. at 10° C./min, isotherm at50° C. for 2 min, heating from 50° C. to 180° C. at 10° C./min. Thedynamic-mechanical properties were carried out by rheogoniometer Ares(temperature gradient 2° C./min, frequency 6.28 rad/s).

Table 1 reports the characterization data of the HDPE and of themixtures with the additive of Example 4.

The fluorinated additive results homogeneously distributed also at thehighest concentration (20%) and it substantially acts as a plasticizer,since the specimen containing the additive shows a modulus decrease andan increase of the elongation at break with respect to the specimenwithout the additive. The melting point does not change, therefore thereare neither alterations of the polyolefin crystallinity, norinteractions at a molecular level. The melting enthalpy decreases in anapproximately proportional way to the content of the fluorinatedadditive in the blend, confirming that there are no meaningful losses ofthe additive during the preparation steps of the masterbatches.

Example 8

Use of the Additive of Example 5 to Modify the Surface PP Properties(Added Additive Amount 1-3%)

A masterbatch formed by 20 parts by weight of additive of Example 5 andby 80 parts of polypropylene having MFI equal to 34 g/10 min (230° C.,2.16 kg), was prepared. The masterbatch was prepared by charging thecomponents in a Brabender mixing cell at 190° C. for 20 min (30 rpmrate).

The masterbatch cold discharged from the cell appears as amacroscopically homogeneous white, plastic solid. The masterbatch at 20%of additive was milled in a screw propeller mill at room temperature.Subsequently blends with PP having additive concentrations of 1% and 3%respectively were prepared in a Brabender cell, following operatingmodalities similar to those described in Example 7.

The additivated PP was then moulded in a plate press at 230° C. for 5min between 2 aluminum sheets having a 0.3 mm thickness.

The surface of the PP plates was characterized by determining thecontact angle with water and, respectively, with hydrocarbons todetermine the hydrorepellence and the surface resistance to liquidshaving a low surface tension. The static contact angle with n-hexadecanewas measured by the sessile drop method by a Kruss® G23 instrument atroom temperature. The angle measure was taken by photograph after 30seconds of contact of the drop with the surface.

The results are reported in Table 2.

From the Table it results that hexadecane completely wets thepolypropylene surface (oleophilic, non resistant to liquids of lowsurface tension). The hexadecane on the additived polypropylene formsdiscrete and stable drops with measurable contact angles. Thefluorinated additive, notwithstanding its polymer nature, is thereforeable to appear on the surface lowering the surface energy. In particularit is observed that by thermal post-treatment cycles at 135° C., andwith percentages of additive higher than 1%, hexadecane drops having ahigh contact angle, of the order of 40°-50°, can be obtained. This meansthat the polypropylene additived with the additives of the presentinvention becomes oleorepellent and non wettable by liquids having a lowsurface tension, also of hydrocarbon nature.

The measurements of the contact angle with water show an increase of thecontact angle with water from 80°-90° for PP as such at 98°-102° for theadditived polyolefin.

Example 9 (Comparative)

Homogeneity Evaluation of the Mixtures of HDPE and a Perfluoropolyether(Fomblin®)

According to known addition processes of the prior art, differentamounts of perfluoropolyether oil Fomblin® YR were adsorbed in thedeliberately created porosities of the hydrogenated resin HDPE. In thisway HDPE mixtures containing various amounts of the fluorinated oil wereprepared.

The used Fomblin® YR 1800 had the following physical properties:

Molecular weight Mn (NMR): 7,250.

Kinematic viscosity (ASTM D455, 20° C.): 1,850 cSt (1.85.10⁹ m²/s).

Density (ASTM D891, 20° C.): 1.2 g/ml.

The mixtures containing an amount by weight of perfluoropolyether higherthan 2% are macroscopically heterogeneous and show the presence of oilyresidues on the surface and local unhomogeneities, such as for examplecraters and accumulations. Mixtures containing respectivelyconcentrations of 2% and 0.5% by weight of Fomblin® YR 1800 wereprepared in mixing cell. From the mixtures specimems were mouldedaccording to the procedure described in Example 7. The tensileproperties of the obtained specimens were determined at 23° C. accordingto ASTM D1708.

The obtained results are reported in Table 3.

From the examination of the Table it is shown that while the modulus ofthe specimens corresponding to the different mixtures remainssubstantially unchanged, in the material containing 2% of additive thereis a substantial worsening of the break properties (stress andelongation at break). This means that in the moulded material theadditive distribution is not homogeneous and defects are present.

It is therefore not possible to prepare masterbatches with this mixture.

Example 10 (Comparative)

Test of Preparation of the Masterbatch of the Polyolefin with thePerfluoropolyether Polyamide

10 g of fluorinated polyamide of Example 1 and 90 g of PP having MFI=34g/10 min are introduced into a Brabender mixing cell. The blend isheated at 190° C. for 30 minutes (stirring blade rate 30 rpm). At theend it is cooled at room temperature and discharged. In the cooled massan unhomogeneous distribution of the polymer fluorinated additive in thepolyolefin is macroscopically observed, with surfacing of liquid andviscous phases which can be mechanically removed.

The fluorinated additive is therefore not compatible with thepolyolefin.

The result does not change by heating the blend at a higher temperature(230° C.), or using in the blend the polyamide of Example 2, orsubstituting PP with HDPE.

It is therefore not possible to prepare homogeneous masterbatches withpolyolefins by replacing the invention additive with the fluoropolyetherpolyamides which are an additive component.

Example 11

Proof of the duration in the time of the surface hydra- andoleo-repellence properties of a polyolefin resin additived with theinvention additive in an amount of 3% by weight.

An amount of masterbatch at 20% prepared in Example 8 was added to a PPsample so as to have a final amount of additive equal to 3% by weight. Aspecimen of the so prepared resin, obtained by moulding between twoaluminum sheets as described in Example 8, is kept suspended for 8 hoursover a becker half full of distilled water maintained at the boilingtemperature.

At the end the specimen is dried and the contact angle is determinedboth with water and with n-hexadecane, obtaining the values shown inTable 4, wherein the contact angle values in the two solvents of theuntreated specimens are reported by reference.

The test shows that the specimen maintains the hydra- andoleo-repellence properties even after quick ageing by contact with watervapours for the above indicated time.

Example 12

Synthesis and Characterization of the Tertiary Bis-amide, Produced byReaction of the Components a)+b)

144 g of N,N-diethylethylendiamine and 1 Kg of diethyl esterperfluoropolyether having molecular weight 600 and the followingstructure:

C₂H₅OCOCF₂O(CF₂CF₂O)_(p)(CF₂O)_(q)CF₂COOC₂H₅ with p/q=2

are introduced in a 2 liters polycondensation reactor, equipped withanchor stirrer.

The reaction mixture is heated at 80° C. under nitrogen atmosphere fortwo hours while the ethanol which is released during thepolycondensation is distilled. The temperature is increased to 100° C.and the reactor is connected to the vacuum source (1 mm Hg) for 4 hours.

The obtained product is hot discharged from the reactor bottom whichappears in the form of a yellow-brown coloured oil.

Viscosity at 20° C.: 50 mpa.s.

Example 13

Preparation of the Additive in Functionalized Polyethylene

In a 2 liters polycondensation reactor 500 g of polyethylenefunctionalized with maleic anhydride are introduced, having thefollowing properties:

Melt Flow Index (ref. Ex. 4): 4.2 g/10 min,

Maleic anhydride content: 0.4% by weight,

Tm 90° C.

The mass, is melted at 120° C. and 500 g of the fluorinated amideprepared in Example 12 are added, heating for one hour. 1000 g of aplastic white solid which is milled and powdered, are discharged.

Example 13A

Preparation of a masterbatch by reaction of the product obtained byreaction of a) with b) with the functionalized polyolefin c) directly inthe hydrogenated resin.

The masterbatch is prepared by introducing the components in Brabendermixing cell at 230° C. for 20 minuti (30 rpm rate), mixing 10 parts byweight of tertiary bis-amide of Example 12 with 5 parts by weight ofpolyethylene functionalized with maleic anhydride equal to that used inExample 13 and 85 parts by weight of polypropylene having MF (ASTMD1238) 34 g/10 min. The obtained masterbatch appears as amacroscopically homogeneous plastic solid.

Example 13B (Comparative)

Compatibility Test of the Compound Obtained from the Reaction of a)+b)with the Hydrogenated Resin

Example 13A is repeated omitting the addition of polyethylenefunctionalized with maleic anhydride.

In the mixing cell, operating under the same conditions, one does notsucceed in forming a homogeneous mixture of the tertiary bis-amide withpolypropylene.

Example 14

Use of the Additive Prepared in Example 13 to Modify the SurfacePolypropylene Properties

A masterbatch formed by 10 parts by weight of the additive prepared inExample 13 with 90 parts by weight of polypropylene having MFI (ASTMD1238) 34 g/10 min is prepared, feeding the two components in aBrabender mixing cell at 230° C. for 20 min. (30 rpm rate). Themasterbatch is cold discharged from the mixing cell and it appears as amacroscopically homogeneous white solid. Then it is milled in a screwpropeller mill.

The masterbatch is further mixed with another aliquot of the same aboveused polypropylene so as to obtain a final concentration of additive of2%.

The following specimens are prepared:

polypropylene used for preparing the masterbatch;

the masterbatch (concentration 10% by weight of additive) and of theadded polypropylene to the masterbatch (concentration 2% of additive).

The specimens are prepared by moulding the material in press at 230° C.for 5 min. between two aluminum sheets. The specimen thickness is of 0.3mm. The oleo-repellence test is carried out on one of the two surfacesof the specimens to verify the resistance of the specimen surface toliquids.

The static contact angle with water-hexadecane is determined.

The results are reported in Table 5, which shows that also at aconcentration of 2% in the resin, the additive is able to confer to thematerial oleo-repellence, since the contact angle keeps on high values,comparable with those of the specimen prepared from the masterbatch.

Example 15

Resistance Test to Abrasion on PP Specimens Containing 3% by Weight ofAdditive

Specimens with the composition of Example 11, prepared as described inExample 8 and having a 0.3 mm thickness, are subjected to an abrasioncycle using a Taber abrasimeter, CD10 grindstone, according to ASTMD1044. At the end of the abrasion cycle the specimen thickness wasreduced of about 5 microns, which corresponds to about 1.5% of thethickness.

After having cleaned the treated surface of the specimen, the contactangle with water and with n-hexadecane is determined. The results arereported in Table 4.

The obtained data show that the hydro- and oleo-repellence propertiesare substantially maintained also by the new surface of the specimenformed with the abrasion cycle. The test shows that the additive isdistributed in a substantially homogeneous way in the specimen.

TABLE 1 Example 7: tensile properties and thermal transitions of HDPEand of the respective masterbatches with the additive of Ex. 4 at 4% and20% by weight concentrations HDPE + additive HDPE conc. 4% conc. 20%modulus (MPA) 830 646 665 stress at break (MPA) 32.4 34.8 29.3 strain atbreak (%) 647 730 763 Tf* (DSC, ° C.) +130 +130 +130 ΔHf** (DSC, J/g)181 173 153 Tg (DMS, ° C.) n.d. −118 −119 *Melting point in secondscanning **Second melting enthalpy

TABLE 2 Example 8: use of the additive of Ex. 5 to modify the sur- faceproperties (resistance to liquids having a low surface tension) of thepolypropylene Contact angle (n-hexadecane) % by weight of additive 00°*** 1 10°-15° 3 22°-28° after specimen re-baking at 135° C. for 4 min.0 0°*** 1 18°-20° 3 45°-50° ***Completely wetted surface

TABLE 3 Example 9 comparative: tensile properties and thermal tran-sitions of HDPE and of the respective masterbatches with Fomblin ® YR atconcentrations 0.5% and 2% by weight HDPE + Fomblin ® YR HDPE conc. 0.5%conc. 2% modulus (MPA) 830 930 900 stress at break (MPA) 32.4 31.5 20.5strain at break (%) 647 680 190 Tf* (DSC, ° C.) +130 +130 +130 ΔHf**(DSC, J/g) 181 173 153 Tg (DMS, ° C.) n.d. −118 −119

TABLE 4 Examples 11 and 15: resistance test to quick ageing andresistance test to abrasion on PP specimens containing a final amount ofadditive of 3% by weight. Contact angle Specimen treatment water(n-hexadecane) Untreated specimen 93°-102° 45°-50° Quick ageing 103° 40°(Ex. 11) Abrasion test 100° 38° (Ex. 15)

TABLE 5 Example 14: use of the masterbatch prepared according to Example13 to modify the surface properties (resistance to liquids having a lowsurface tension) of polypropylene Contact angle % by weight of additive(n-hexadecane) 0 0° 2 58°-60° 3 65°-70°

What is claimed is:
 1. Additives for hydrogenated resins, formed byfunctionalized perfluoropolyethers and functionalized polyolefins, saidadditives being obtained by reacting the following components: a)bifunctional perfluoropolyethers having a —COOR end group optionally inadmixture with monofunctional perfluoropolyethers having —COOR endgroup, wherein R═H, C₁-C₁₀ alkyl, the number average molecular weight ofbifunctional and monofunctional perfluoropolyethers being in the range500-5,000, b) mono, bi or polyfunctional hydrogenated monomers having asfunctional groups aminic groups, c) polyolefins having functionalgroups, said polyolefin formed by C₂-C₄ monomers, said functional groupsobtained by grafting with maleic anhydride; reacting in a first step a)with b), or a) with mixtures of monomers b) having a differentfunctionality, until disappearance of the —COOR end group of componenta), and in a second step reacting the product obtained from the reactionof a) with b) with the functionalized polyolefins c).
 2. Additivesaccording to claim 1, further comprising neutral perfluoropolyether oilshaving a molecular weight in the range of 2,000-10,000 component d)). 3.Additives according to claim 2, wherein the amounts of each componenta)-d), expressed as percentages by weight, are the following: componenta) 30-70% by weight; component b) 1-30% by weight; component c) 10-70%by weight; component d) 0-20% by weight; the sum of a)+b)+c)+d) beingequal to 100% by weight.
 4. Additives according to claim 1, wherein thebifunctional (per)fluoropolyethers and the monofunctionalperfluoropolyethers mentioned in a) have one or more of the followingunits statistically distributed along the chain: (C₃F₆O);(CF₂(CF₂)_(x′)CF₂O) wherein x′ is an integer equal to 1 or 2; (CFYO)wherein Y is F or CF₃; (C₂F₄O); (CR₄R₅CF₂CF₂O) wherein R₄ and R₅ areequal to or different from each other and selected between H or Cl, andwherein one fluorine atom of the perfluoromethylene unit is optionallysubstituted with H, Cl or (per)fluoroalkyl having from 1 to 4 carbonatoms.
 5. Additives according to claim 4, wherein the bifunctionalcompounds of a) having perfluorooxyalkylene units statisticallydistributed along the chain are selected from the group consisting of:(a′) —CF₂—O—(CF₂CF₂O)_(p′)(CF₂O)_(q′)—CF₂—  (VIII) wherein: p′ and q′are numbers such that the p′/q′ ratio is comprised between 0.2 and 2 andthe molecular weight is in the above mentioned range; (b′)—CFX′^(I)—O—(CF₂CF(CF₃)O)_(r′)—(CF₂CF₂O)_(s′)—(CFX′^(I)O)_(t′)—CFX′^(I)—  (IX)wherein: X′^(I) is —F or —CF₃; r′, s′ and t′ are numbers such that r′+s′is in the range 1-50, the t′/(r′+s′) ratio is in the range 0.01-0.05,r′+s′ being different from zero, and the molecular weight is in theabove mentioned range; (c′)—CF(CF₃)(CFX′^(I)O)_(t′)(OC₃F₆)_(u′)—OR′_(f)O—(C₃F₆O)_(u ′)(CFX′^(I)O)_(t′)CF(CF₃)—  (X)wherein: R′_(f) is a C₁-C₈ perfluoroalkylene; u′+t′ is a number suchthat the molecular weight is in the above range; t′ can also be equal tozero; X′^(I) is as above indicated; (d′)—CF₂CF₂O—(CF₂(CF₂)_(x′)CF₂O)_(v′)—CF₂CF₂—  (XI) wherein: v′ is a numbersuch that the molecular weight is in the above range, x′ is an integerequal to 1 or 2; or (e′)—CF₂CH₂—(OCF₂CF₂CH₂O)_(w′)—OR′_(f)O—(CH₂CF₂CF₂O)_(w′)—CH₂CF₂—  (XII)wherein: R′_(f) is a C₁-C₈ perfluoroalkylene; w′ is a number such thatthe molecular weight is in the above range; the end groups of thebifunctional perfluoropolyethers component a) being of the —COOR typewherein R═H or C₁-C₁₀ alkyl.
 6. Additives according to claim 4, whereinthe monofunctional perfluoropolyethers used in a) in admixture withbifunctional perfluoropolyethers have the following structures:A′O(C₃F₆O)_(m)(CFYO)_(n)—  IB) wherein Y is —F, —CF₃; A′=—CF₃, —C₂F₅,—C₃F₇, —CF₂Cl, C₂F₄Cl; the C₃F₆O and CFYO units are randomly distributedalong the (per)fluoropolyether chain, m and n are integers, the m/nratio is ≧2, m and n have values such that the molecular weight iswithin the limits indicated for component a); C₃F₇O(C₃F₆O)_(m)—,   IIB)wherein m is a positive integer and is such that the number averagemolecular weight is in the limits indicated for component a);(C₃F₆O)_(m)(C₂F₄O)_(n)(CFYO)_(q)  IIIB) wherein: Y is equal to —F, —CF₃;m, n, and q, different from zero, are integers such that the numberaverage molecular weight is in the limits indicated for component a);being the end group of the monofunctional perfluoropolyethers —CF₂—COOR,R being as above.
 7. Additives according to claim 1, wherein the amountof monofunctional perfluoropolyethers in the mixture with thebifunctional perfluoropolyethers in a) is in the range 0-90% by weight.8. Additives according to claim 1, wherein the monomers component b),are selected from the group consisting of: (b1) monoamines of formula R₁—NH₂ wherein R₁ is a linear aliphatic or cycloaliphatic C₁-C₂₀ alkylwith a number of carbon atoms of the ring from 4 to 6, optionallysubstituted with C₁-C₄ alkyl groups; or R₁ is an aryl group optionallysubstituted with linear or branched C₁-C₄ alkyl groups, the total numberof the carbon atoms being in the range 6-20; (b2) diamines of formulaNR_(2A)R_(3A)—R_(1A)—NH₂, wherein R_(1A)=linear or cycloaliphatic C₂-C₁₂alkyl radical with a number of carbon atoms of the ring from 4 to 6,optionally substituted with C₁-C₄ alkyl groups, or C₆-C₁₂ aryl group;R_(2A) and R_(3A), equal to or different from each other, are hydrogenor linear or branched C₁₋C₅ alkyl group; (b3) aromatic tetramines offormula (NH₂)₂—Ar1—Ar1—(NH₂)₂ with Ar1=phenyl, optionally substitutedwith C₁-C₄ alkyl groups.
 9. Additives according to claim 8, wherein thecomponent b) is selected from the group consisting of stearylamine, acompound of (b2) and a compound of (b3).
 10. Additives according toclaim 1, wherein in component c) the functionalized polyolefins areselected from the group consisting of the following polymers:polypropylene homopolymer, copolymers of polypropylene, high densitypolyethylene (HDPE), linear low density polyethylene (LLDPE) graftedwith functionalized monomers capable of reacting with the aminic groupsof the reaction product of a)+b), or copolymers or terpolymers ofethylene containing an ethylene monomer selected from vinyl acetate (VA)or n-butylacrylate (E/nBa), optionally in the presence of carbon oxide(CO).
 11. Additives according to claim 2, wherein the end groups areperhalogenated with —CF₂X, with X═F or Cl.